Place half the stuffed peppers in a single layer in center of a large sheet of heavy duty foil. Bring foil together to create a tightly sealed packet. Repeat with remaining peppers.

Place on grill, cook covered, for 15 minutes. Carefully open foil packets (steam will be released) to expose peppers. Sprinkle each pepper with cheese. Continue to grill, covered, for 10 to 15 minutes or until filling is heated through, cheese is melted and peppers are tender. Sprinkle with remaining green onion.